The Question:

Can you tell me who invented the ATM and when?

The Answer:

Don Wetzel is credited with inventing the Automated Teller
Machine in the late 1960's, while working for a company in Dallas
called Docutel.

A graduate of the University of Loyola in New Orleans (Class of
1951), Wetzel played professional minor-league baseball for three
years after college before putting his bachelor's degree in foreign
trade to work at IBM. He joined Docutel in 1968 and received the
patent for the ATM in 1973.

Here is a comprehensive interview
with Wetzel, in which he discusses the complete history of the
ATM's development.